Engine - Baffling? .... You Bet it is!!
Added 11/8/2005 - 1283.3 approx. Total hours (1090.7 By Me)
I had been previously warned that the engine
baffling takes a lot of time. Rumors had the timeframe anywhere
between 40 and 70 hours to get all the baffling done. Engine
Baffling, for those who don't understand it, is the metal and rubber
"sealing" surfaces that go around the tops of the cylinders. You
want air to enter the cowl through the inlets, flow over and directly
down through the cylinder fins, and flow through ducts to misc. areas
as required...with no leakage of air. Poor baffling causes hot
engine spots, and can cause damage. Day one on the baffling, I
thought it looked much easier than I had anticipated, based on the
rumors. The initial baffle assmebly goes very quickly and is very
much in step with the provided plans. Reality hit shortly after I
got into actually installing the baffles....
First, there was the complication of my Lightspeed ignition module that
is mounted in the same spot as the rear baffle support bracket.
The first few photos show how I dealt with this. I removed
the bracket, chopped the baffle support down a bit, then re-fabricated
my own ignition coil bracket that moves the coil about 3/32" to 1/8'
further forward, adds washers to raise it another 1/16", and also
mounts it about 3/32" to 1/8" further to the right side of the engine.
Sounds like a lot, but it's just a simple piece of aluminum
angle, drilled and cut the right way.
Once that was finished, I quickly ran into issues when installing the
rear baffle on the right side. Around the vernatherm (I think
that's what it is) the baffle fit too tight. It took a bunch of
trial-fitting to trim down a spot on the baffle to fit in the proper
place. In addition, to get the baffles on, the oil return tube
need to be temporarily disconnected, but that's very minor. It is
becoming apparent that there are many variations of blocks for IO-540's
now. Mine works great attaching things where some other builders
don't have luck, but at the same time, it's obvious that mine is
different from the one Van's created the FWF kit from. The angle
bracket on the rear of the right rear bafflle didn't work great for me.
I had to trim some baffle and bracket away to get it to fit in.
Then, when it did fit, the hole that attaches it to the block
didn't line up with the hole in the bracket, so I had to drill the
bracket for the right spot.
Moving on to the front baffles, bending the ramps was no fun at all,
although with time, it got done reasonably well. I'm not clear on
one thing with the front right side ramp...there are 2 holes where the
alternator boss mount attaches. One hose is used also to fasten
the air ramp. But, if you do that, the alternator will not be
able to be mounted flush to the block...and you'll need a washer or
shim on the other alternator boss mount hole. On the left side,
the ramp attachement bracket for the engine boss mount was obviously
built for a different engine as well. My engine only has one hole
drilled and tapped on the flat surface. The bracket clearly looks
to be designed for one that has a hole in a slightly mroe rearward
place. So, time to make my own bracket. Photos are shown below.
My bracket is mounted slightly more rearward on the ramp, due to
constraints. I also worried about the big 3/4" hole in the old
bracket....why was it there? Did I need that? But a call to Anh
verified that we think it was just a lightening hole, so all should be
Then, when donig the front facing baffles (on the inner air ramp area),
the Right side goes well, but the left side needs some very aggressive
trimming to fit around the MT propeller governor (used on the Hartzell
also). Once I had that trimmed enough, I could get it in and out
Eventually, you get to a point where you trim back the front edge of
the air ramps even with the cowl edge. That's fine, but it won't
work that well if done exactly flush. Once the seal is in, you
have to remember that you can only move your cowl forward about 1/8"
before you hit the spinner backplate, so you need to make sure it's not
too tight in that area. That means you might want 1/4" gap
between the ramp and the cowling. But, what also isn't mentioned
is that you might not want to trim it all off the ramp, but trim the
cowling instead. I trimmed my ramp, and ended up trimming the
forward most rivet hole right out of that front left baffle ramp where
the duct attaches. No big deal, but I wouldn't have had to trim
as far if the cowling were trimmed instead. Either way, you'll
want enough clearance to make it easier to drop the cowl, without
making it a poor fit that will leak badly. So, it didn't take
long to get to a point where I realize that this baffling is going to
take some time.
Note: Right now would be a good time to make sure if you're this
far along that you've completed your FAA registration. I found
out recently that I probably should have done it a while
back....because you can.